The dominant firm in health insurance

Blue Cross, the largest insurer of hospital costs in most parts of the U.S., has a varying market share by area. This paper examines the factors affecting the market share of Blue Cross by state. The regression analysis finds that the Blue Cross discount has an important impact upon market structure and that certain regulatory factors have had an impact while others, such as the premium tax, have not. Hypotheses related to the effects of consumer demand and the structure of the industry on Blue Cross market share are also tested and largely rejected.